Unit 2b: The Cardiovascular System

KA 1: The structure and function of arteries, capillaries and veins Subtopics: Structure and function of blood vessels Exchange of materials between tissue fluid and cells This used to be in a spider diagram format!

KA1: Learning Outcomes State the similarities and differences in composition between blood plasma and tissue fluid Describe the process of the exchange of materials between tissue fluid and cells State what happens to the tissue fluid after pressure filtration occurs State the role of the lymphatic vessels after pressure filtration occurs

What do you see in a blood smear? RBCs WBCs Plasma Platelets

What does plasma contain?

Blood Plasma Blood plasma is a watery yellow fluid that contains many dissolved substances: Glucose Amino acids Respiratory gases Plasma proteins Ions

Pressure Filtration Blood arrives from the artery into a smaller vessel called an arteriole

Pressure Filtration 2. This blood is at a higher pressure than the blood in the capillaries

Pressure Filtration 3. As blood is squeezed through the narrower capillaries, it undergoes pressure filtration and much plasma is squeezed out into the space surrounding the cells. This is NOW called TISSUE FLUID.

Tissue Fluid Tissue fluid is similar in composition to blood plasma EXCEPT that tissue fluid does NOT contain larger molecules such as plasma proteins. The proteins are too large!!

Pressure Filtration 4. The tissue fluid contains a high concentration of soluble food molecules and dissolved oxygen compared to the cell. Therefore, these substances DIFFUSE down the concentration gradient from the fluid into the cells.

Pressure Filtration 5. At the same time, carbon dioxide and other metabolic wastes DIFFUSE out of the cells and into the tissue fluid to be excreted.

Pressure Filtration 6. Much of the tissue fluid returns to the blood through OSMOSIS Tissue fluid lacks protein and has a higher water concentration than the blood plasma

Pressure Filtration 7. Lymphatic vessels absorb excess tissue fluid and return the lymph fluid to the circulatory system. Tissue fluid that enters the lymphatic vessel is now known as lymph

Lymphatic System Is a part of the circulatory system Comprises of a network of lymphatic vessels that carry a clear fluid called lymph towards the heart

Capillary cross-section Lymph vessel passes into lymphatic system Venule (blood leaves at low pressure) Arteriole (blood enters at high pressure) Lymph vessel capillary Respiring cells

TASK: Colour your lymph vessels!

Lymphatic Disorders Kwashiorkor Malnutrition causes tissue fluid to accumulate in the spaces between cells and blood capillaries in the abdominal area Tissue swell up due to excess fluid Prolonged lack of protein causes plasma protein in blood to be so low that that tissue fluid cannot return to the blood by osmosis as there is no difference in water concentration.

Lymphatic Disorders Elephantiasis Larvae of a specific parasitic worm enter the body and invade the lymphatic system. Once they mature in adult worms, they reside in and block lymphatic vessels. This obstruction along with excessive growth of neighbouring tissues (since excess fluid cannot be cleared away from a specific area) results in an enormous enlargement of the area (particularly in the legs)

KA1: Learning Outcomes State the similarities and differences in composition between blood plasma and tissue fluid Describe the process of the exchange of materials between tissue fluid and cells State what happens to the tissue fluid after pressure filtration occurs State the role of the lymphatic vessels after pressure filtration occurs